Depth sensing cameras based on time-of-flight technology work by measuring a runtime of emitted light between a camera and the scene. In order to receive a valid measurement a certain amount of light needs to be reflected and arrive at a sensor (e.g., the camera) of the depth sensing systems. The sensor usually comprises a plurality of pixels to sense the reflected light and to produce a depth image of the scene. Pixels with insufficient signal strength may be noisy and/or invalid, which may limit the range and/or the resolution of the camera. A longer exposure time of the sensor may lead to more accurate measurements. However, a long exposure time is often not feasible due to eye safety reasons of a person exposed to the emitted light, power consumption and thermal stress of the device itself. A long exposure time may also limit a frame rate of the depth sensing system.
Furthermore, depth sensing systems may suffer from motion artifacts. In order to calculate depth images from raw data with Signal to Noise Ratio four or more sequential sub-images are often recorded. Camera motion and/or a motion of an object in the scene may cause these sub-images to be inconsistent, which may result in invalid depth data, called motion artifacts and, in turn, hinder the use of multiple images for the generation of a single depth image.
There is a desire to improve the generation of depth images of depth sensing systems.